This only works when there is a direct line of sight to the underside of the roof which obviously has limitations.
Roof moisture survey.
A nuclear roof moisture survey is the most accurate way to locate trapped moisture in ballasted roofs.
The damage from a leak in the membrane can be at a minimum a nuisance inside the building but the damage to the roof from the trapped moisture can be very costly.
Moisture surveys are conducted using a prelocated grid pattern throughout the roof area at which the device is placed and readings are recorded.
The infrared roof moisture survey was conducted to locate and define areas of moisture insulation within the roof system.
The grid pattern is typically 5 to 10 feet apart.
By the time the scan commenced the surface temperatures were sufficiently cooled to allow necessary temperature differentials.
An under roof moisture survey is accomplished when the thermographer determines differences in mass between and wet and dry substrate by looking up at the roof from the inside of the building.
The plotting of wet areas is derived from the recorded readings and identified on a roof plan.
The nuclear technology is able to distinguish between multiple levels of moisture and can operate in a wide range of weather conditions on any type of slope roof.
If a set of drawings or roof plan is not available prepare a plan and report sheets for each section being surveyed or better still use the tramex moisture mapping app.